Use new entry function name in qwasmwindow test

Use qwasmwindow_harness_entry instead of the old createQtAppInstance.

Change-Id: I381dd43d9144fe70f055c19db4cd95f90313883b
Reviewed-by: Piotr Wierciński <piotr.wiercinski@qt.io>
Reviewed-by: Mikołaj Boc <Mikolaj.Boc@qt.io>

tests/manual/wasm/qwasmwindow/qwasmwindow_harness.html

@@ -4,7 +4,7 @@
     <script type="text/javascript" src="qwasmwindow_harness.js"></script>
     <script>
         (async () => {
-            const instance = await createQtAppInstance({});
+            const instance = await qwasmwindow_harness_entry({});
             window.instance = instance;
 
             const testSandbox = document.createElement('div');